1. Field of the Invention
The present invention relates to a storage virtualization technique.
2. Description of the Related Art
An apparatus (storage virtualization apparatus hereafter) which is capable of virtually providing a storage device existing in an external storage subsystem to an upper order apparatus as an internal storage device is known. An example of this type of apparatus is disclosed in Japanese Unexamined Patent Application No. 2005-107645, for example.
According to this technique, a plurality of paths (alternative paths) connected to the storage device in the storage subsystem are provided between the storage virtualization apparatus (first storage control apparatus) and the storage subsystem (second storage control apparatus) such that even when a fault occurs on one of the plurality of alternative paths, the storage virtualization apparatus can access the storage device in the storage subsystem via another alternative path. A technique disclosed in Japanese Unexamined Patent Application No. 2006-40026, for example, is known as a path switching technique.
When only one storage virtualization apparatus is provided and the storage virtualization apparatus malfunctions, the storage device in the storage subsystem cannot be provided to the upper order apparatus. To reduce the likelihood of this problem, a method of providing the storage virtualization apparatus with redundancy may be considered. For example, at least one more storage virtualization apparatus is connected to the storage subsystem connected to the storage virtualization apparatus.
When this method is employed, a logical device configuration enabling access to the storage device in the storage subsystem must be identical in all of the storage virtualization apparatuses interposed between the upper order device and the storage subsystem. This is so that the upper order apparatus can access the same storage device in the storage subsystem via any of the storage virtualization apparatuses. (For example, the logical device configuration may include a combination of a number (LDEV#) of a logical storage device (LDEV) and a number (VDEV#) of a virtual storage device (VDEV), a LUN within the storage subsystem, which is mapped to the VDEV#, and so on.)
However, if a person (a manager of the storage virtualization system, for example) must construct the logical device configuration in an added storage virtualization apparatus, this places a load on the person. Moreover, it is not always possible to construct an identical device configuration to the logical device configuration in the existing storage virtualization apparatus accurately in the added storage virtualization apparatus since human input errors may occur.
The storage virtualization apparatus may be replaced by another storage virtualization apparatus, but in this case also problems such as those described above may occur since the logical device configuration constructed in the original storage virtualization apparatus must be constructed in the replacement storage virtualization apparatus.